As the global economic integration evolves, economic exchanges and people contacts among countries is getting increasingly popular. Accordingly, in a CDMA system, a user has a common demand for international roaming.
Presently in the world, most operators of mobile communication system have entered into agreements on signaling connections between countries and settlement between the operators for CDMA roaming, so that the international roaming of a Post-Paid Charging subscriber can be properly implemented. However, for a Pre-Paid Charging subscriber, the charging for which is always accomplished in the Home Public Land Mobile Network (HPLMN) because account information of the subscriber is stored on a Home Service Control Point (SCP) in the HPLMN. In other words, each time acting as a calling party or a called party, the Pre-Paid Charging subscriber must be authenticated by the Home SCP, which determines whether to establish a call or not and the duration of the call; here, the call can be made only if the Pre-Paid Charging subscriber has an account with enough balance. Furthermore, during the call of the Pre-Paid Charging subscriber, the HPLMN would monitor the call and charge for the subscriber in real time. Therefore, in view of above characteristic of the Pre-Paid Charging service, the Pre-Paid Charging service has a higher requirement for the network and a further requirement that the call control and charging rules must be determined by the HPLMN. As a result, most operators are unable to provide international roaming service for Pre-Paid Charging subscribers at present.
Even if the international roaming of a Pre-Paid Charging subscriber is allowed, the function of real-time charging for the Pre-Paid Charging subscriber in international roaming can not be completely implemented based on protocols of the CDMA intelligent network system in the art.
1. In the case where a Pre-Paid Charging subscriber becomes a called party after internationally roaming to the Visited Public Land Mobile Network (VPLMN):
If the Mobile Switching Center/Service Switching Point (MSC/SSP) in the VPLMN has a Wireless Intelligent Network (WIN) capability, then the Home Location Register (HLR) in the HPLMN dispatches a Trigger configuration of a Pre-Paid Charging subscriber to the MSC/SSP in the VPLMN when the terminal of the Pre-Paid Charging subscriber carries out location registration. However, usually there is no coordination on signaling addressing configuration at the intelligent network between operators in two countries/regions, respectively, therefore, no signaling exchange is carried out between the MSC/SSP in the VPLMN and the SCP in the HPLMN; as a result, in the case where a Pre-Paid Charging subscriber in international roaming becomes the called party, the SCP in the HPLMN cannot charge for the Pre-Paid Charging subscriber in real time.
For example, if the calling party is a subscriber in the HPLMN, due to the fact that the called process of an intelligent network subscriber is triggered at the initial calling office, i.e., at the MSC/SSP in the HPLMN, and the TANSWER (i.e., the called party answers) and TDISCONNECT (i.e., the called party releases) have to be reported by the MSC/SSP in the VPLMN because of special requirements of CDMA protocols; thus, the reporting may fail due to the network, resulting in that the SCP in the HPLMN cannot charge for the called party accurately.
If the calling subscriber is also in the VPLMN, the initial calling office of the call is the MSC in the VPLMN. In this case, after identifying the called number as a HPLMN number, the MSC in the VPLMN relays the call to the Gateway Mobile Switching Center in the HPLMN for triggering the called service logic of CDMA network, the signaling process herein is essentially identical to that in the case where a HPLMN subscriber calls a subscriber has roamed to the VPLMN; similarly, the SCP in the HPLMN therefore cannot charge for the called party.
2. In the case where a Pre-Paid Charging subscriber initiates a call after internationally roaming to the VPLMN:
If the MSC/SSP in the VPLMN has a WIN capability, then the HLR in the HPLMN dispatches a Trigger configuration of a Pre-Paid Charging subscriber to the MSC/SSP in the VPLMN when the terminal of the Pre-Paid Charging subscriber carries out location registration. However, usually there is no coordination on signaling addressing configuration at the intelligent network between operators in two countries, respectively, therefore, no signaling exchange is carried out between the MSC/SSP in the VPLMN and the SCP in the HPLMN; in this case, when the Pre-Paid Charging subscriber initiates a call, the MSC/SSP in the VPLMN cannot authenticate the Pre-Paid Charging subscriber, as the result, the Pre-Paid Charging subscriber is unable to initiate the call.
If having no WIN capability, the MSC/SSP in the VPLMN would not carry out signaling exchange with the SCP in the HPLMN; as the result, the Pre-Paid Charging subscriber in international roaming is out of the control of the SCP in the HPLMN, and therefore the Pre-Paid Charging subscriber may initiate calls freely, just like a Post-Paid Charging subscriber.
In the conventional art, the CDMA intelligent network cannot control and charge for a call of the Pre-Paid Charging subscribers in international roaming, and therefore cannot provide an international roaming service for the Pre-Paid Charging subscriber.